Headlight



` Feb. 24,1931.

w. H. woon HEA'DLI GHT Filed Dec. il, 1926 william H woad InventorPatented Feb. 24, 1931 WILLIAM H. WOOD, OE SOUTH E'UGLID, OHIO I HEADLIGHT Application med December-1, 1926. serial No. 151,955.

This invention relates to vehicle headlights and has for its object theprovision of a new and improved refiector, usable either alone or inconj unction-with a lens of suitable type for producing a light beampart of which shall be projected a long distance ahead of the vel hiclein the form ofa concentrated ray and otherparts of which shall becastdownwardly and laterally at pointsinearer to the vehicle, and thisvthroughout a considerable range of therein, spaced a short distanceapart vertically, the purpose being to enable an eleva tion ordepression of the refiecti-d beam according to traffic conditions, whilemaintaining the light pattern substantially uniform. Another obj ect'ofthe invention is to produce a reflector having 'the above-describedcharacteristics which shall in addition exhibit a l substantialdegree'of tolerance as regards ax- 'ial displacement of the filamentrelatively to the focal region, namely a degree of tolerance which is asgreat as the accidental variations between lamp bulbs of the same size,make, and type. This application is a continllation of my formerapplication filed July ject-matter` is common thereto.

As set forth in my application filed February 26, 1926, and June 7,1926, Serial Nos. 90,781 and 114,167 `respectively, I make at least thelateral margins of the reflector substantially paraboloid with its axisapproximately horizontal, since thelight pattern produced by thisportionof the reflector is least distorted by such a vertical movementof the light'source as is produced bya change from one filament to theother. The rays falling on other parts of the reflector are castdownwardly and laterally by modifying-'the remaining portions of thereflector as herein.- after described.

In the drawings accompanying and forming a part of this application Ihave shown a preferred physical embodiment-of my inventive idea. Figs.land 2 are respectively 1a yvertical displacement of the light source.

21, 1936 Serial NO- 123,944, so far as the sub-i lution by dotted linessolely to facilitate this the axis a-a and the curve itself is prosleelevation anda front elevation of a rje- Hector embodying myimprovements; Fig. 1 being shown partly in section corresponding A tothe line 1-1 of Fig. 2; and Figs. 3 and 4` illustrate alternative modesof deriving the curve employed for the central vertical zone illustratedin Fig. 2. l

My improved reflector is characterized essentially by `the relationbetween its horizontal section X-X and its vertical section Y-'-Y. Theformer section comprises a pao0 rabola with its axis a-b substantiallyhorizontal; the latter section comprises a para-y bolic curve having agreater downward incli-' nation at every point than that of the paraoloid at an equivalent point. 'Ihe portions andB of the reflectorsurface located adjai cent to the horizontal section arepreferablysegments of a surface of revolution .produced by revolving thehorizontal parabola 4about its own axis a-b, and the focal point of thisportion of the reflector is indicated at fA in Fig. 1. If this surfaceof revolution were continuous it would produce the complete paraboloidindicated at A B by dotted lines in Figs. 1 and 2. In practice I use forreflect- 75 ing purposes only that portion of such paraby oloid as liesat and near the horizontal central plane at each side of the refiector,but show the remainder of such surface of revodescription.

The vertical axial section corresponding to Y-Y in Fig. 2 conforms vto4a second parabola having its vertex `located in front ofy the vertex ofsaid 'first paraboloid.` This last curve can be either la simpleparabola generated as shown in Fig. 3 or the curve illustrated in Fig.4.v The curve G illustrated 'in Fig. 3 is a simple parabola whereinevery point is equidistant from the focal 90 point4 f and from-*the lineD-D perpendicular to the axis a-aand known as the directrix. The curveHin Fig. .4 likewise has a focal point f" but the same is located aboveduced asfollows. l, vA directrix D-D is drawn perpendicular to the axisa-a.^- A

line m-/m is drawn through `the focal point f and intersecting the axis(LQ-a at the point m', Thereupon a vertical line M-y-M 10o is drawn.through-the focalpoint f andinvis dan@ 'parallel to :lr-'D' as far n theopposite side thereof as m is displaced laterally fromthefoeal`.poii1t.V A. point 1n/"isl now found on this line equi'distantfrom the vline M-M .and the point m and this is 'a point on the curve.Likcwisea linen-,4a

' tersects theline cir/ a at a. A' vertical line ter as -n is displacedinwardly of the focal point and a point n is found on that line i' oneside ola G shown in Fig. `3 `bolicjcurve I-I shown N-N is drawn parallelto`D -D and spaced the same distance inside of the latequidistantfromN-N and from nf. Likewise .a line p-p is drawn lthrough the focal.

point intersecting the axis aa-at p and a vertical'line P-P isv drawnparallel to D-D" and as far heh-ind that line as pf is located infrontof the focal point thus enabling the location of a point p0 equidistantfrom P-P and from p. 'The curvethus produced can be considered asessentially/a parabola' having its focal point displaced to of the axisaa and its axis a-a inclined downwardly and forwardly compared with thefirst named axis. -It

vwill be noted thatA a line S',

S passing through the focal point f.

and from the axis ria. Either the parabor the modified parain Fig. .4can be employed as a template for the central vertical vtex of the curvewhich defines the vertical zone C-C. 35

- fined by thevertical section 'Y-'Y shall lean Vfmwaadlyiand downwardlyat every point The essential thing is that the curve deas compared withthe paraboloid surface defined by the side wings; and it is desirablefor practical reasons, though substantially immaterial optically,'thatthe versection be located in front of 'that of the hori- 'zontal sectionsinc'ein this way the front of v 15 the reector becomes' more-nearlycircular.

A Urdinariily the focal length of the curve de- .ined by the verticalsection is less than that' of thev parabola defined by the horizontalsection XX as in conjunc- 5o tion with the ydescribed relation of the.vertices to' bring said lfocal -pointssubstantiall-y into the samevertical linebut the-relation of the focal points is much less importantthan that of the surfaces as defined in this paragraph and is not sogood a criterion of my invention as the comparative inclination of thecurves both because. of possible variations and because `of thedifficulty vof l'ocating the focal point in an existing reflector.

'It must not be supposedv that the axis cfg-c'v constitutes the axis ofrevolution about which the portion C+C-of the. reflector is produced.'The axis c-'c is merelythe axis of the curve defined by the centralvertical section; in other words of thevertical temvthis template aboutan feature of my A n related D dlrectly tothe directrix IT-D', thepoints .so-48 being equidistant from such directrix' lwings. These canbe regarded asr `surfaces gradually mergin the edgesof-jA bviously sucha by' first making a metal'punch according to the description heretoforegiven and when the same have-1.

plate. Each half ofthe portion Ce-.C is produced byswinging thecorresponding half of axis oblique to cc but much further away; forexample, the

-upper half of this zone may be considered Vtransverse curvature of theportionI C-C 1 listhan the curvature ofthe parabolid' i' reason thevertex ofthe portion C-C`should adjacent-to its vertex.- It is for thisbe located forward of the vertexof the paraboloid `A-B invention, aswell as lbeing easily proven. In 'referring to these vertices I do not,imply that either or both of the surfacesmust be actually extended toor throughthe axis but refer more particularly to the imaginary'extension 'of the surfaces as illustrated in 4Fig-1 in dotted .lines.

, The portion C fallsinside of 'and below the paraboloid Af B at the topof the reiiector. 'At the-bottom center ofthe reliectorth'e two surfacesmay merge'exactly as-here Shown,

or either may fall somewhat within or Without the other.This'relation'is not important optically, so long as the two lower outer.margins of this portion fall below the paraboloid AB as indicated at'gi-1g in Fig. 2. Likewise the twoupper marginsof the portion C mustalways remain below the par..

raboloid Af C as indicatedat ii-fi' in I1`Iig.'2. This same relationmust prevail throughout the four remainingquadrants of thev`l reflector,

`namely that the portionsl E -E above thel center must lie whollybelowand inside, while the p ortion .E-E below thecente'r must Aliewholly below and outside ,ofthe paraboloid surface A B dened'brtlrefsideI ransition and with those of C. reflector is bestA produced beenfollowed tothis point it will be found that the remaining sections arecomparatively small in area and very nearly matohedfin form so that itis an easy matter to fashion these quadrantsinto connecting surfaces.It" is also permissible to iiat some or all of the'y reflector intovertical striations, if desired.

In case this is done, care must be taken not to, obliterate theessential curvatures and lrelations heretofore described, namely thatthe vertical section conform to a parabola of `oneof the typesmentioned, every point of which shall lean forwardly and downwardly ascompared with the paraboloid which \andthis is an important Iconstitutes the inedian horizontal zone and having its vertex located infrontof the vertex of such paraboloid. derstood that the words upper7and loivei'f above and below and downwardly eniployed in-thisspecification relate't-o positions compared with the earths surface whenthe headlight is in its intended Operative position on a vehicle.

Having thus described iny invention what I claim is:

l. A headlight reflector whose horizontal axial section is parabolic atpoints adjacent -to and extending inwardly from its lateral niargins',and whose vertical axial section is parabolic at points adjacent to andextend ing inwardly froinits upper and lowerinargins, the focal lengthof the veitical section being less than that of the horizontal section,and the vertex of the parabola which defines the vertical section beinglocatedy in front of the vertex of the parabola which defines the.horizontal section.

2. A headlight reflector whose horizontal axial section is parabolic atpoints adjacent to and extending inwardly froni its lateral inargins,and whose vertical axial section is parabolic at points adjacent to andextending inwardly froni its upper and lower niargins, the vertex of thevertical section being located in front of the vertex of the horizontalsection and the axis of the vertical section being below the axis of thehorizontal section, in front of the focal point thereof.

' 3. A headlight reflector having portions Aimmediately adjacent itshorizontal axis de- ,finedI by segments of a paraboloid, and having acentral vertical zone. whose longitudinal section is defined by aparabolic curve hav- `ing a focal point and an inclined axis, the focaldistance of such curve being less than that of the first naniedparaboloid and the focal point of such curve being located in'substantially the saine vertical line with the focal point of said rstparaboloid, the transverse section ofsaid central zone being of lesscuri vature than said paraboloid.

4. A headlight reflector whose horizontal section is in large part aparabola and whose vertical section both above and below the axis is inlarge part a paraboliccurve of shorter focal distance than the firstnamed parabola, the focal point of said last nanied curve lyingsubstantially on the saine vertical line with the focal point of saidlparabola.

5. A'headlight reflector whose horizontal section is a parabola andwhose vertical secl .tioii-isa parabolic curve of shorter focal distancethan the first nanied parabola, the focal point of said last named curvelying substantially on the same Vertical line with the focal point ofsaid parabola and the axis of said last curve being downwardly inclinedrel'- ative to' the axis of said parabola.

lt should be unlength of the vertical section being less than that ofthe horizontal section. the vertical central zone having a transversecurvature less than that of the horizontal zone andthe axis of thevertical section being inclined for-1` ivardly and downwardly ascompared with that of the horizontalsection, and the vertex of thevertical section lying in front of that of the horizontal section.

T. A headlight ieeetor whose horizontal and vertical axial sections areboth in large part substantially parabolic curves, the focal length ofthe vertical section being less than that of the horizi'intal section.the vertical central zone having a transverse curvature less than thatof the horizontal zone, the vertex of the vert-ical section'beinglocatedin front of the vertex ofthe horizontal section. and the heel of thereflect-or having a plane portion perpendn'ular tothe refiector axis,which port-ion merges with both the horizontal and vertical zones.

H. A headlightI reflector whose horizontal and vertical axial sectionsare in large part substantially parabolic curves of unequal size. the folal length of the vert' :al section heilig the smaller. the verticalcentral zone l having a transverse curvature less than that of thehorizontal zone. and the lateral inargins of said central vertical zonebeing located outside of the paraboloid defined by said horizontal zonethroughout all the region i the focal length ofthe vertical sectionbeing the smaller, tlievertex of said vertical section l being locatedin front of the vertex of said horizontal section, and said verticalsection having a greater forward inclination at every point than isexhibited at equivalent pointsy by the paraboloid defined by saidhorizontal zone.

l0. A headlight reflector having portions at and for a substantialdistance on each side of itsliorizontal axial plane defined by segmentsof a paraboloid surface, and having theI portions at and near itsvertical axial plane leaned forwardly and downwardly as comparedwith'the first mentioned paraboloid surface at equivalent points, thevertex of all portions at; and iiear\ the axial. plane being located infront of the vertex of said paraboloid. y i

11. A headlight reflector having portions at and near its horizontalaxial plane defined by a paraboloid surface whose axis is substantiallyhorizontal and having theportions at and near its vertical axial planeconformlll) - ing in large part toa :parabola which' is:

` everywhere leaned forwardly and downward@ ly as compared with saidparaboloid at equivv yalent points, the transverse curvature of saidnear the-vertical axial 'section defined longi'- tudinallyby alcurvewhich leans downwardly and forwardly as compared with said parab` oloid'and defined laterally by a line of last named portions ybeing less thanthat of the first named portions, and the lateralmargins yof said lastnamed portions lying every-.f '.-wherebelow the paraboloid surfacedefinedv by said firstA named portions."-

112. A headlight-redactor havingiportions" at and near its horizontalaxial plane definedby a paraboloid surface whose aiisis substan#tiallyliorizontal, and having portions at fandsmaller .curvature thansaid paraboloidgpthe .marglns'of said lastI namedportions being yjoinedto -theadjacent .margins of'said first named portions by segments whichlie wholly4 -l below 'saidparaboloid surface. l f

. '13; 'A headlight relectorhavingy portions at each sidev extendingboth above and below` the horizontal plane defined by-a paraboloid` isurfacewhoseaiis is substantially'horizon-lg `tal,andy having portionsatand near itsvertical axialplane'which exhibit atl every point adownward' leaning as. comparedlwth the extended surface ofsaidfirst--paraboloidat equivalent points, themarginsfoi` said last fnamedportionsbeing joinedfto-the adjacent margins of said rst named portionsby seb- Y ments 'which lie wholly below said paraboloid surface, theportions of said, reflector lying at eachl side ofthe'centralfvertical'zone themselves having vertical zones of reducedhori- Zontal-'curvature superposed thereon'.

In testimony whereof I` hereunto -aiix my Signature.. v Y v V t .WILLIAMH. woon.'

CERTIFICATE OF CORRECTION.

Patent No. I, 793,663, Granted February 24, 1931, to

WILLIAM H. WOOD.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 3,lines 58 and 59, claim 5, after the word "is" respectively insert thewords in large part; and that the said Letters Patent should be readwith these corrections therein that the same may conform to the recordof the case in the Patent Office.

Signed and sealed this 21st day of April, A. D. 1931.

M. J. Moore, (Seal) Acting Commissioner of Patents.

